1. Field of the Invention
The present invention relates to a system and a method for feeding fuel to a diesel engine which make use of fuel oil containing fine particles of solid fuel such as pulverized coal or the like.
2. Description of the Prior Art
In a conventional diesel engine as shown in FIG. 2, fuel oil is fed from a fuel tank 101 through a fuel feed pump 102 to a fuel injection pump 103, then it is introduced into a fuel valve 108 as high-pressure fuel, and it is injected from a nozzle hole 109 into a combustion chamber of the engine. However, in the case of a diesel engine, when mixed fuel consisting of pulverized coal and water or fuel oil is pressurized to a high pressure and is injected to be burnt, a plunger would seize due to solid material of the mixed fuel within the plunger chamber and continued operations of the engine could not be effected.
It is to be noted that in FIG. 2, reference numeral 104 designates a plunger accommodated within a barrel 105 of the fuel injection pump 103, numeral 106 designates a delivery valve of the fuel injection pump 103, numeral 107 designates a fuel feed pipe, numeral 110 designates a needle valve of the fuel injection valve 108, numeral 111 designates an oil reservoir provided on the upstream side of the needle valve 110 within the fuel injection valve 108, and numeral 112 designates a spring for biasing the needle valve 110.
Inherently, in a high-pressure fuel injection pump, fuel having had its solid material filtered out is employed, and it is improper to directly feed mixed fuel consisting of solid material of pulverized coal and fuel oil to a fuel injection pump because the plunger will seize.